1. Field of the Invention
The present invention relates to a measuring head, and more particularly to a measuring head which is to be used in surface texture measuring instruments, contour shape measuring machines and the like and has a retractable device for shifting the sensing pin from its measuring position to a predetermined retracting position.
2. Description of the Related Art
A conventional surface texture measuring instrument, contour shape measuring instrument or the like for measuring the surface roughness or contour shape of a work has a sensing pin at the tip and a measuring head provided with a seesaw member supported to be swingable pivoting on a fulcrum member, a urging member for urging the seesaw member in one direction, and a detector arranged on the other side than the sensing pin with respect to the fulcrum member and detecting the displacement of the sensing pin by detecting the displacement of the seesaw member. By causing this measuring head to traverse along the measured face of the work and the sensing pin to trace the measured face, the surface roughness or contour shape of the work is measured.
In a measuring head having such a structure, in order to protect the sensing pin when a work is set or any discontinuous face of the work is measured, there is provided a retracting device for moving the sensing pin.
Such a conventional retracting device has a mechanism in which a solenoid is disposed near the seesaw member, and the sensing pin is moved from its measuring position to a prescribed retracting position and vice versa by turning on and off power supply to the solenoid and thereby swinging the seesaw member.
Another retracting device has a mechanism in which a cam is turned by an electric motor, the seesaw member is swung by the lift of the cam, and the sensing pin is thereby caused to retract (e.g. see the Japanese Utility Model Application Publication No. 5-75606).